Screwpumps

ABSTRACT

A screw pump of the kind comprising a screw of the archimedean type which is adapted to be rotated in an inclined trough to pump a liquid up the trough characterised in that the screw is comprised by at least two separate co-axial screw portions each having helical flights and mounted on a common central shaft, the screw portions being disposed in an inclined trough having a plurality of separate portions of complementary cross-section, there being an inlet for liquid to be pumped at the lower end of each said trough portion, and an outlet for pumped liquid at the upper end of at least the uppermost portion.

United States Patent 1191 Mar. 12, 1974 Rowley SCREWPUMPS [75] Inventor: Robert Rowley, Congleton, England {22] Filed: May 5, 1972 [2]] Appl. No.: 250,500

[30] Foreign Application Priority Data 2/1927 Hoffman 415/72 2,131,453 9/1938 Patteson 415/75 FOREIGN PATENTS 0R APPLICATIONS 505,253 12/1954 Italy 415/72 1,152,612 8/1963 Germany 415/73 2,025,692 12/1970 Germany 415/72 Primary ExaminerC. J. Husar Attorney, Agent, or Firm-Norris & Bateman [57] ABSTRACT A screw pump of the kind comprising a screw of the archimedean type which is adapted to be rotated in an inclined trough to pump a liquid up the trough characterised in that the screw is comprised by at least two separate co-axial screw portions each having helical flights and mounted on a common central shaft, the screw portions being disposed in an inclined trough having a plurality of separate portions of complementary cross-section, there being an inlet for liquid to be pumped at the lower end of each said trough portion, and an outlet for pumped liquid at the upper end of at least the uppermost portion.

6 Claims, 4 Drawing Figures PATENTEU MAR 12 I974 SHEET 3 OF 4 SCREWPUMPS This invention concerns screw pumps of the kind (hereinafter termed of the kind referred to) comprising a screw of the archimedean type which is adapted to be rotated in an inclined trough to pump a liquid up the trough.

It has been known to provide two or more separate screw pumps of the kind referred to to pump supplies of liquid atdifferent levels to a common elevated level or to different elevated levels.

It is an object of the present invention to provide a single screw pump capable of'use for such an application.

According to the invention a screw pump of the kind referred to is characterised in that the screw is comprised by at least two separate co-axial screw portions each having helical flights and mounted on a common central shaft, the screw portions being disposed inan inclined trough having a plurality of separate portions of complementary cross-section, there being an inlet for liquid to be pumped at the lower end of each said trough portion, and an outlet for pumped liquid at the upper end of at least the uppermost portion.

The invention will be further apparent from the following description with reference to FIGS. 1 to 4 of the accompanying drawings, which show longitudinal cross-sections through four different screw'pump arrangements embodying the invention.

Referring now to the drawings, it will be seen that each of the embodiments have various features in commen, like parts being numbered with like reference numetals on all the figures.

Essentially each of the screw pumps is comprised by an archimedean screw, generally indicated by the reference numeral 10, which is adapted to be rotated by means of a motor 11 in an inclined trough 12. Each of the screw pumps comprises an axial shaft 13 carried in bearings 14 and 15 located adjacent its extreme lower and upper ends respectively.

In accordance with the invention each of the archimedean screws 10 includes two separate co-axial screw portions adapted to perform different pumping duties.

Referring now more particularly to FIG. 1 it will be seen that the helical flights 16 on the lower portion of the screw 10 are of smaller diameter than those 17 on the upper portion, the inclined trough 12 having separate portions of complementary cross-section.

The pump of FIG. 1 is adapted to pump liquid from a reservoir 18 at the extreme lower end of the screw 10 to a reservoir 19 adjacent the extreme upper end of the screw 10. A feed pipe 20 communicates with the interior of the trough 12 at the extreme lower end of the portion of the screw 10 of larger diameter whereby additional liquid to be pumped to the reservoir 19 can be introduced at this level. It will be understood that even though this latter supply of liquid may be of greater flow rate than the former there will be no tendency for it to run downwardly in the trough 12, because the portion of the screw 10'of larger diameter is capable of carrying liquid upwardly in the upper part of the trough at least as fast as it is fed thereto by the feed pipe 20.

Referringnow to FIG. 2, it will be seen that the screw once again comprises an upper portion of greater diameter than a lower portion. In this embodiment, the flights 16 of the lower portion terminate to leave a space on the shaft 13 between the two screw portions and a sealing disc 21 is secured to the shaft 13 to close the cross-section of the screw at the lower end of the upper portion. Liquid may be pumped from a reservoir 22 for discharge at 23 at the upper end of the lower screw portion, there being egress from the trough 12 at this position, simultaneously with liquid being pumped from a feed pipe 24 to the trough 12 at the lower end of the upper screw portion and to a reservoir 25 at the upper end of the complete screw 10. The disc 21 minimises leakage of liquid from the supply 24 downwardly in the trough 12. In this embodiment the upper portion of the screw is of course intended to handle a greater flow of liquid than the lower portion.

FIGS. 3 and 4 show arrangements similar to that of FIG. 2 save that in FIG. 3 the lower portion of the screw is of greater diameter than the upper portion, and in FIG. 4 the two portions are: of equal diameter. The arrangements of FIGS. 3 and 4 are intended for applications where the flow rate from positions 22 to 23 is greater than or substantially equal to that from positions 24 to 25, respectively.

It will be appreciated that it is not intended to limit the invention to the above example only, many variations, such as might readily occur to one skilled in the art, being possible without departing from the scope thereof.

Thus, for example, the screw pumps may include more than two portions of the same or different diameters for even more complex multipurpose applications.

What is claimed is:

l. A screw pump comprising a screw of the Archimedean type, an inclined trough in which said screw is located, drive means for rotating said screw in said trough, an inlet at the lower end of said trough for receiving liquid to be pumped, an outlet at the upper end of said trough for dispensing pumped liquid, and a further inlet in said trough at an intermediate level part way between said first mentioned inlet and said outlet for receiving further liquid to be pumped from said level towards said outlet by said screw.

2. A screw pump according to claim 1, characterised in that said screw consists essentially of two co'axial ax ially separate screw portions each having helical flights and mounted on a common central shaft, and said intermediate level input is located at the bottom of the upper screw portion.

3 A screw pump according to claim 2, wherein said common central shaft is mounted for rotation in bearings adjacent its extreme upper and lower ends respectively and is driven by a motor connected with said upper end. 7

4. A screw pump according to claim 2, wherein said screw portions are of different effective diameter and said trough has separate portions ofcorresponding size associated with said screw portions.

5. A screw pump according to claim 4, wherein the lower of said screw portions is of. smaller effective diameter than the upper.

6. A screw pump of the kind comprising a screw of the archimedean type which is adapted to be rotated in an inclined trough to pump a liquid. up the trough characterised in that the screw is comprised by at least two separate axially spaced apart co-axial screw portionseach having helical flights and mounted on a common central shaft, the screw portions being disposed in an inclined trough having a plurality of separate portions of complementary cross-section, there being an inlet for liquid to be pumped at the lower end of each said trough portion, an outlet for pumped liquid at the upper end of at least the uppermost portion, and a sealing disc secured to said shaft at the lower end of an upper screw portion thus to close the cross-section of the screw at said lower end of said upper screw portion. =1: 2: 

1. A screw pump comprising a screw of the Archimedean type, an inclined trough in which said screw is located, drive means for rotating said screw in said trough, an inlet at the lower end of said trough for receiving liquid to be pumped, an outlet at the upper end of said trough for dispensing pumped liquid, and a further inlet in said trough at an intermediate level part way between said first mentioned inlet and said outlet for receiving further liquid to be pumped from said level towards said outlet by said screw.
 2. A screw pump according to claim 1, characterised in that said screw consists essentially of two co-axial axially separate screw portions each having helical flights and mounted on a common central shaft, and said intermediate level input is located at the bottom of the upper screw portion.
 3. A screw pump according to claim 2, wherein said common central shaft is mounted for rotation in bearings adjacent its extreme upper and lower ends respectively and is driven by a motor connected with said upper end.
 4. A screw pump according to claim 2, wherein said screw portions are of different effective diameter and said trough has separate portions of corresponding size associated with said screw portions.
 5. A screw pump according to claim 4, wherein the lower of said screw portions is of smaller effective diameter than the upper.
 6. A screw pump of the kind comprising a screw of the archimedean type which is adapted to be rotated in an inclined trough to pump a liquid up the trough characterised in that the screw is comprised by at least two separate axially spaced apart co-axial screw portions each having helical flights and mounted on a common central shaft, the screw portions being disposed in an inclined trough having a plurality of separate portions of complementary cross-section, there being an inlet for liquid to be pumped at the lower end of each said trough portion, an outlet for pumpEd liquid at the upper end of at least the uppermost portion, and a sealing disc secured to said shaft at the lower end of an upper screw portion thus to close the cross-section of the screw at said lower end of said upper screw portion. 